CODEWITHSUNDEEP
ioscocoa-touchgpscore-location
Jacob R
Jacob R

Reputation: 430

Objective-C iPhone check location periodically

My iOS application relies heavily on GPS and I tried writing a method that helps conserve battery but I am having little success.

I created an NSTimer that fired every 15 seconds. Every time the method was called, it would increment an int time up by 1. If int time reached 20(5 minutes) it would turn off the location updates and set a bool isStopped to true. Every time the method ran and int time was above 20, it would increment another int, int time2, up by 1. If the method was ran and int time2 was equal to 4, it would start the location updates again and set time2 to 0.

Then in the didUpdateLocation: method for the location manager, I have an algorithm that would first check if the bool isStopped was true, if it was true then it would check the new location's horizontal accuracy and make sure it was under 10. Then it would check the newLocation with a location object named coords and check to see if they were greater than 9 meters apart. If they were not, it would stop location updates again and return. If they were, it would continue to another algorithm where it would check the new location object against some arguments. If it passed the coords location object would be set with the new location object, the time and time2 ints would be set to 0, the isStopped would be set to false, and the whole process would start all over again.

In short, after 5 minutes of no location changes, the location updates would be stopped and periodically checked every 1 minute to see if the user had moved at least 10 meters from the previous location that passed all requirements. When the user does move far enough, it starts the process all over again and the user has to not move 10 or more meters for 5 minutes before it starts the periodic checks. The thought behind this is to do only few second checks every minute when the user isn't moving much instead of constantly having the location services running.

Now here's the problem I run into, when the location updates stop. The NSTimer stops running while the app is in the background.

Could I somehow schedule a background task to run the loop between the 1 minute checks? Does anyone have any better ideas? Or any ideas on solutions to this?

Upvotes: 0

Views: 1255

Answers (1)

AdamG
AdamG

Reputation: 3718

A while ago I asked a question that features all the different ways that you can run GPS in the background.

CLLocationManager geo-fencing/startMonitoringForRegion: vs. startMonitoringForSignificantLocationChanges: vs. 10-minute startUpdating calls

You have to do specific things in order to maintain GPS in the background. A NSTimer would not suffice, since you need to register your app to be allowed to keep it running in the background after ten minutes. You minimally have to run the GPS every 10 minutes in the background to keep your app running.

Anyway, the methods in the above post should answer your question.

Upvotes: 1

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